Method for the extraction of oils from grain materials and grain-based food products

Abstract

A method of obtaining oil from grain materials such as rice bran, wheat mill feed, rapeseed, amaranth, and similar grains, by stabilizing the oil contained in the grain material (when necessary) while increasing the porosity of such grain material; extracting oil from the grain material by contact with a solvent in vapor form; and, separating extracted oil/solvent compositions into fractions containing various amounts of saturated and unsaturated oils. A solvent in vapor form is also used to remove oils from: previously-extracted oil seeds, which were extracted using a less efficient extraction method; flaked or crushed vegetable matter; and grain-based food products such as chips, crackers and noodles.

What is claimed is: 
     
       1. A method for extracting oil from oil-bearing grain materials or grain products which comprises: preparing a vapor of a solvent for the oil which is not a solvent for protein in the grain materials or grain products;   introducing the vapor into a container below a horizontal bed of oil-bearing grain material or grain product from which substantially no oil has been extracted while the bed of rice bran is being moved horizontally;   passing the vapor through a horizontally moving bed of oil-bearing grain material or grain product so that the vapor contacts the grain material;   the pressure and temperature of the vapor and the grain material or grain product being such that at least a portion of the vapor condenses upon contact with the grain material and extracts oil from the grain material or grain product, forming a solvent/oil solution and a marc from which oil has been extracted; and   thereafter, while continuing to move the bed of grain material or grain product horizontally, passing a gas downwardly through the bed of grain material or grain product at a velocity sufficient to substantially separate the solution from the grain material or grain product.   
     
     
       2. A method as defined by claim 1 wherein the solvent vapor is drawn through the grain material or grain product by a partial vacuum. 
     
     
       3. A method for extracting oil from rice bran which comprises: preparing a vapor of methyl acetate or ethyl acetate;   introducing the vapor into a container below a horizontal bed of rice bran from which substantially no oil has been extracted while the bed of rice bran is being moved horizontally;   passing the vapor through the moving bed of rice bran so that the vapor contacts the rice bran;   the pressure and temperature of the vapor and the rice bran being such that at least a portion of the vapor condenses upon contact with the rice bran and extracts oil from the rice bran, forming a solvent/oil solution and a marc. from which oil has been extracted, while maintaining a temperature in the bed of not more than about 210° F.; and   thereafter, while continuing to move the bed of marc and solvent/oil solution horizontally, passing a gas downwardly through the bed at a velocity sufficient to separate at least some of the solution from the marc.   
     
     
       4. A method as defined by claim 3 in which the ethyl acetate vapor is under a partial vacuum when it comes into contact with the rice bran and some of the ethyl acetate remains in vapor form after it passes through the bed of rice bran.